innobase_create_index_def(): Add parameter new_primary.

innobase_copy_index_def(): Simplify the documented algorithm,
and try to implement it properly.

innodb-index.test: Replace CHECKSUM TABLE with something more stable and
useful.  The test passes on an older BitKeeper snapshot:

ChangeSet@1.2475.18.9, 2007-05-08 11:16:41+02:00, jbruehe@mysql.com +1 -0
  Raise version number after cloning 5.1.18-beta

But it fails on a newer one where the statement
	alter table t1 add primary key (a), add key (b(20));
results in fast index creation:

ChangeSet@1.2500.1.40, 2007-06-01 20:06:13+04:00, kostja@bodhi.(none) +2 -0
  Merge bodhi.(none):/opt/local/work/mysql-5.0-runtime
  into  bodhi.(none):/opt/local/work/mysql-5.1-runtime
  MERGE: 1.1810.2984.14